Safety tube



Feb. 17, 1942.

cQ H. ZIMMERMAN SAFETY TUBE Filed April 27. 1940 Patented Feb. 17, 1942SAFETY TUBE Charles H. Zimmerman, Akron, Ohio, assignor to WingfootCorporation, Wilmington, Del., a eorporation of Delaware ApplicationApril 27, 1940, Serial No. 332,018

8 Claims.

The present invention relates to safety tubes of the type in which thereis a plurality of chambers. Particularly this invention is shown inconnection with a two-chambered tube of the type disclosed in the LeePatent No. 2,173,065 in which one chamber is enclosed within a secondchamber, the walls of the chambers being joined at their bases. The tubeis provided with a single valve for inflating both chambers.

An object of the present invention is to provide a valve for quicklyinflating a tube of Ithe character shown particularly in the Lee patent,whereby the same requires only substantially about the'same time toinflate as the ordinary inner tube.

Another object of this invention is to inflate the outer chamber of thetube rapidly while permitting slow filtration of air to the inner tubeafter inflation and/or partially during inflation.

More particularly, my invention contemplates employing in a tube of thecharacter described a valve having separate ports for supplying air toboth chambers simultaneously, but at different rates, the inner chamberbeing supplied with air at the slower rate whereby the Walls thereofwill not be distended to place a strain on same that might injure thewalls or cause detachment of same from the Walls of the outer chamber.

Other objects of the invention will appear hereinafter as thedescription thereof proceeds, the novel features, arrangements andcombinations being clearly set forth i n the specification and in theclaims thereunto appended.

In the drawing:

Fig. 1 ls a transverse cross-section through a tube embodying myinvention;

Fig. 2 is an enlarged cross-section through the valve embodying myinvention; and

Fig. 3 is a cross-section taken along the line 3-3 of Fig. 2.

The use of a restricted opening in the Wall of the inner chamber, as inthe aforesaid Lee patent, provides for positive controlled deflation incase of b1ow-out or failure of either chamber and does not rely on theclosing of a valve, asin some safety tubes, to give quick inflationand/or deflation with a consequent trapping of air in the good chamber.Such valves may fail to work, especially when traveling at high speeds,since centrifugal force may keep same from working. Also such valves maybe destroyed or impaired, such as when the tire goes flat or anobstruction is hit.

It is desirable, however, to insure quick inflation but it is notdesirable to eliminate the valuable feature of a metered outlet for theair from either chamber upon failure of the other. My present inventionembodies a device that will will meet these requirements and possess allthe advantages of the aforesaid Lee tube, while providing for quickinflation.

In the drawing I have shown in cross-section a tube comprising an innerchamber A and an outer chamber B formed by two continuous annular tubesjoined by a common wall I0 at the base. The wall of chamber A is formedof rubberized fabric while the wall I2 of chamber B is preferably formedof stretchable rubber so that it may expand and ll a tire carcass.

The valve of this invention is formed with a metal stem I3 having alongitudinal bore I4 which is restricted at its end by a reducing plugI5 having a small port I6 therein which permits air to enter chamber Aonly at a relatively slow rate. This port IB is preferably not over .05inch in diameter and usually smaller. The purpose of this will appearlater. The plug I5 seats against a shoulder on the valve stem and ispress-fitted into the stern of the valve after cure of the inner chamberA or of the completed tube, whereby air can enter and leave the innerchamber A rapidly during cure through the larger opening |8, thusreducing the curing time.

lThe stem is embedded in rubber and has a rubber base, as in valves ofthis character, and is provided with the usual check valve or valveinsert I9 to prevent the back flow of air out of the valve stem duringor after inflation,

The base is formed with a lateral extension 20 formed with a passage 2|communicating with a port 22 in the valve stem. 'I'his extension has across-section, such as shown in Fig. 3. The outer end Aof extension 2'0is provided with a boss 23 which is inserted in a corresponding openingin the wall so that the passage 2| will communicate with chamber B. Thevalvey and extension are secured to the inner side of wall before thebase of the tube is closed and is vulcanized into an integral unit withthe wall during the process of vulcanizing the inner chamber or carcass,as in the Lee Patent No. 2,090,210, showing the process of making such atube.

During cure, in order to prevent rubber from floyving into the passage2|, I provide a metal insert or cap 24 which is inserted in the open endof the passage and after cure this is removed and the outer chamberformed by adding the wall I2 thereto.

During inflation the air enters through the valve stem and isdistributed to chambers A and B through the ports I8 and 22. Since theport I8 is very small as compared to 22, which latter has an effectivecross-,section equal to that provided in the usual single-tube valveconstruction, only a small percentage of air enters the chamber A andmost of it goes to chamber B. 'I'his causes a collapse of the wall I! asindicated somewhat diagrammatically at 2'5 in Fig. 1. While the chambersdo not have the desired quantity of air in same the pressure isequalized in both chambers and the total quantity of air required forboth chambers is in the tube.

Since the fabric carcass A is shaped initially as shown in the drawing,there is a 'natural tendency to regain its former shape afterdeflection. Thus air seeps back through passages 2| and ports 22 and I6into the chamber A from chamber B and eventually the required air is inchamber A. If not equalized prior to operating a vehicle, it requiresonly a few minutes for the equalization to ftake place after the wheelon which the tube is mounted is rotated,as during use of the vehicle towhich same is applied. Centrifugal force aidsthe wall I I to regain itsnormal shape.

Of course one seldom has to inflate from a zero pressure to the desiredamount and the usual inflation to get three to five additional pounds ofair in the tube will not collapse the wall .I2 materially. v

In using this invention, when one inilates the tube the pressureregistered on the pressure gauge will be the same as that which existsafter equalization of the Aamounts of air in chambers A and B, sincethere is only an exchange of quantities of air with no resultant drop inpressure.

When a blowout occurs or a failure of wall of either chamber results,the air leaks out of the two ports both communicating with said bore andeach communicating with different ones of said chambers to supply uidthereto from said bore, one of said ports having a substantial effectivecross-section such as to provide for rapid now of uid to its respectivechamber, the other port 'i being of an effective cross-sectionmaterially less than-said first port whereby fluid is supplied to saidrst chamber at afhlgher rate than said seci action of the stress in thewall set up during ingood chamber at a slow rate through the grommetport I6. Thus, as in the aforesaid Lee Patent No. 2,173,065, while thetire eventually goes fiat, the driver is given enough time to bring thevehicle to a safe stop without damaging the tire and/or tube.

If desired the ports I6 and 22 could be interchanged as to size, wherebythe inner chamber A is inflated first with slow inflation of the outerchamber B but this has the objection of requiring some considerable timefor proper inflation and repeated checks to determine when the desiredpressure is reached. It however will provide for slow and positivemetering of the air leaving the undamaged chamber when a blowout occurs.

If both ports I6 and I8 are made small, the same as I6, slow inflationoccurs but a uniform distribution of the air is given to both chambers.Strain on the wall of the inner chamber A is prevented, however, sincethere is no building up of a pressure greater than that in chamber Bunless chamberB is considerably greater in volume than chamber A.

Obviously various changes can be made in the combinations, arrangementsand construction of' the various parts without departing fromA thespirit of this invention and I do not wish to be limited except as mayappear hereinafter in the claims hereunto appended.

What I claim is:

1. A plural-chambered container of the class described comprising atleast two chambers, with a exible wall separating said chambers to allowfor expansion or contraction of said chambers when differentialpressures are exerted in said chambers on opposite sides'thereof, avalve on said container having a bore through which fluid is supplied tosaid chambers/said valve having nation thus forcing some of the uidthrough the communicating ports from said first chamber to saidsecondchamber to equalize the pressures in said' chambers, said ports being inconstant lintercommunication to.equalize the pressures in said chambersat all times, and said second port being of a small enough size topermit only the slow passage of fluid therethrough, thereby providing aninterconnecting passage between said chambers of the effective size ofthe smaller port, whereby upon failure of one chamber the fluid willleak out of the other chamber to the atmosphere through said second portat only a Irela.- tively slow rate of speed.

2. A device as set forth in claim 1 in which the two chambers arearranged radially outward, the one, from the other, with the valve portof larger size supplying the outer chamber.

3. A device as set forth in claim 1 in which the two chambers arearranged radially outward, the one from the other, with the valve portof larger size supplying the outer chamber, and in which the flexiblewall is inextensible, at least at the outer periphery thereof, toprevent expansion thereof beyond predetermined limits, less than thesize of the tire in which the container is adapted to be mounted.

4. A device as set forth in claim l in which the two chambers arearranged radially outward, the one from the other, with the valve portof larger size supplying the outer chamber, and in which the flexiblewall is formed of fabric molded to a predetermined shape whereby ittends to occupy a normal position providing substantially the desiredvolumetric capacities for the two chambers, the flexibility of the wallpermitting movement thereof inwardly of its normal position but beingmolded so as to be inextensible and, therefore, prevented from movementoutwardly beyond its normal position to a material extent.

5. A device as set forth in claim 1 in which the smaller port has aneffective cross-section not substantially larger than that of a .05 inchbore.

6. A plural-chambered container of the class described comprising twochambers located radially outward one from the other, with a iiexiblewall separating said chambers to allow for expansion or contraction ofsaid chambers when differential pressures are exerted in said chamberson opposite sides thereof; a valve on said container having a borethrough which uid is supplied to said chambers, saidvalve having twoports, one of said ports communicating with said bore and outer chamberand having a substantial eflective cross-section such as to provide forrapid'iiow of fluid to its respective chamber, the other portcommunicating with said bore and said inner chamber and being of aneffective cross-section materially less than said first port wherebyiiuid is supplied to said outer chamber at a higher rate than said innerchamber thereby causing a flexing of said wall inwardly out of itsnormal operative position during inflation due to the excessive pressurebuilt up in said outer chamberl because of the more rapid supply of uidthereto, thereby reducing the volumetric capacity of the inner` chamber,said wall being moved outwardly under the action of centrifugal forceunder service conditions thus forcing l, some of the iluid through-thecommunicating ports from said outer chamber to said inner chamber toequalize the pressures in said chambers, said ports being in constantintercommunication to equalize the pressures in said chambers, and saidsecond port being of a small enough size to permit only the -slowpassage of fluid therethrough, thereby providing an interconnectingpassage between said' chambers of the effective size of the smallerport, whereby upon failure of one chamber the fluid will leak out ofthe; other chamber to the atmosphere through said second port at only arelatively slow rate of speed.

7. A valve for use in inflating plural-chambered tubes comprising avalve body having a bore, at least two unobstructed and continuouslyopen ports communicating with said bore for supplying uid introducedinto said bore to different ones of the chambers of a plural-chamberedtube, one of said ports being of substantially small cross-section withan effective size of not substantially more than that of a circularopening .05 inch in diameter, the other of said ports being of asubstantially greater effective cross-section, said ports beingunobstructed at all times and in constant intercommunication, the borebeing provided with a check valve to prevent return flow of fluidsupplied to said bore.

8. A valve for use in iniilating plural-charlibered tubes comprising avalve body having a bore extending therethrough, a port of substantialcross-section communicating with said bore for use in supplying iiuidtoV one chamber of such tube, a second port of substantial cross-sectionalso communicating with said bore and in constant communication withsaid ilrst port for supplying fluid to another chamber of such al tube,said latter port being in alignment with said bore and large enough incross-section to permit rapid ination and deation of the chamber towhich it supplies uid during curing of that chamber, and a` reducingplug having a restricted opening therethrough substantially smaller ineffective cross-section than either of said ports and mounted in saidbore to restrict said second port only, subsequent to the curing of saidsecond chamber, said restricted opening forming a continuously open butrestricted passage between the chambers of said tube when said valve isin use and being small enough in cross-section to provide for onlyslow'passage of uid therethrough whereby, when one of said chambersfails the other of said chambers will be only slowly deated.

CHARLES H. ZIMM'ERMAN.

